1. Field of the Invention
The present invention relates to a three unit zoom lens including, in order from the object side thereof, a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, and a third lens unit having a positive refracting power. The present invention also relates to an image pickup apparatus equipped with such a three unit zoom lens.
2. Description of the Related Art
In recent years, digital cameras that pick up an image of an object using an image pickup element such as a CCD or CMOS sensor have replaced film cameras to become the mainstream. Furthermore, various categories of digital cameras ranging from popular-priced compact type cameras to advanced type cameras for professionals have been developed.
Users of such popular-priced digital cameras generally wish to enjoy easy and simple shooting in various shooting situations anywhere at any time. For this reason, such users favor small size digital cameras, especially cameras that are small with respect to the thickness direction and can be conveniently carried in a pocket of clothes or a bag. Therefore, a further reduction in the size of the taking lens system is demanded. In addition wider angles of field are desired to extend the shooting scenes. Therefore, there is a demand for a zoom lens having a high zoom ratio, a wide angle of field at the wide angle end of its zoom range, and good optical performance.
A three unit zoom lens including, in order from the object side thereof, a first lens unit having negative refracting power, a second lens unit having a positive refracting power, and a third lens unit having a positive refracting power is well known as a zoom lens that can be made small in the collapsed state and easily designed to have a high zoom ratio.
Japanese Patent Application Laid-Open Nos. 2006-195064 and 2007-148052 disclose three unit zoom lenses of this type, in which each lens unit is composed of a plurality of lens components to achieve good optical performance.